Asus N55 random screen flickering/ no backlight problem

Hello forum, I have had a problem for some weeks with this otherwise very satisfiable product.
I have the exact same issue as the guy in this video from 0:40 on: https://www.youtube.com/watch?v=NobMOFBaUzE
Basically, the screen sometimes starts to flicker in the same way as if just connecting a separate monitor. It looks like it is just adjusting the position of the window, as the desktop jumps around to try and orient after the left upper corner. However, often it goes on for a while and then just turns completely black for maybe just a moment, or maybe 20 minutes... . If that happens at least two times shortly after another, I also get those exact same green doted line on the left side of the screen, as in the video.
The backlight is working fine btw., as I can still turn the screen of via key command and then see the brightness drop to natural dark (compared to inferior 'LCD dark'), so it isn't that. Different than in the video, I also don't get full color screens in between, but only black flashes. This could be though because the guy started a program that produces screen flashes on its own maybe.
I actually have a second screen connected at nearly all times, which is not showing any kind of issue whenever this problem appears and on which I can continue to work, so it seems more likely to be hardware related? There was a guy in the comments of the video above, who said he delivered his N55 to technical support, and they sent it back to him, claiming it was a software problem.. . That seems unlikely to me though.
There is no indication on what software specifically could be causing this, as the problem appears nearly completely at random, and there was no special event (like some windows update), which could have started it to begin with when it appeared first. When it comes, it does not matter whether I have a second screen connected or not, or if the laptop is nearly idle or not. It seems to come up more often whenever more demanding processes start (even if they only target one processor and no gpu), but I cannot fully confirm this - only that often the problem appeared exactly when something bigger started. Often enough too though, everything just continues fine.
The guy in the video seems to be able to lure the issue out by starting some sort of test program. As you can see in the comments of that video, many people actually have the exact same problem with that exact same laptop, rendering it even more unlikely to be software related.(cannot be fully excluded though)

I have already searched the web for information on this, but all recommendations always just seem to be to check and exchange the backlight, which is definitely not my problem. The best match -yet no solution-, I only found with a targeted search on the N55 series with that Youtube video, indicating again it to be a model related issue.
So, If someone has any idea here, please, I am eager to know.

 

Usually something like this is per fault of the data cable (either a bad connection or a bad cable). Since an external monitor works fine for you, your display adapter must be okay.

The easiest way to confirm or decry the cable being the fault is to reseat it at the LCD. If still no luck, then you can reconnect it at the board's connection, though it more commonly is strained at the screen.

 

Thanks for replying. Yes, I have figured now it might be that since I found this thread in the forum meanwhile, which describes my problem even more accurately than the video I linked. They guessed it to be the cable, but the guy never called back to provide if it was correct or not sadly.
He also never received answer on how to do this when he asked. I have the same problem, as I know how to disassemble my laptop completely (did a dedust and repaste some months ago), but the screen seems like a solid piece with no screws or visible gaps. Anyway, I will figure it out and then see to post results after sufficient testing.

 

The LCD casing is almost always split into two pieces─a backing and the frame around the screen. The gap is often minimal, and sometimes it requires mild prying.

Not sure whether yours is designed similarly or not, but hopefully you find a way to get to that cable to figure it out.